1. Field of the Invention
The present invention relates to network interface modules and in particular to a network interface module that includes overvoltage protection, line termination impedance having a characteristic signature, other means for testing the telephone company owned portion of a customer loop or means for disconnecting the customer's equipment therefrom.
2. Discussion of the Relevant Art
An individual homeowner at present may purchase and install his or her own telephone equipment and related appliances. The homeowner is responsible for the proper operation of the equipment that he/she has installed. The telephone company may not own the equipment in a subscriber's home and therefore will be responsible only for proper service up to the juncture between the telephone lines and the homeowner's premises. Thus, it is necessary to provide a telephone interface apparatus which is capable of readily disconnecting the homeowner's wiring, installed in the premises, from the telephone company's transmission lines so that when trouble occurs, it could readily be isolated to the telephone company's line or the homeowner's house wiring. If a homeowner experiences a problem with his telephone service it is first necessary for him to determine if it is the telephone company's fault and repairs are needed on their lines or equipment, or if the wiring or equipment the homeowner installed requires repairs. Many devices are now available that provide the function of readily disconnecting the home wiring from the telephone company owned portion of the subscriber loop. Typical of these apparatuses is U.S. Pat. No. 4,910,770 issued to Collins, et al on Mar. 20, 1990; U.S. Pat. No. 4,488,008 issued to T. A. Dellinger, et al on Dec. 11, 1984; U.S. Pat. No. 287,583 issued to T. J. Smith, et al on Jan. 6, 1987, and U.S. Pat. No. 4,624,514 issued to Smith on Nov. 25, 1986.
These devices, although providing the necessary function of severing the telephone company owned portion of the customer loop from the homeowner's portion of the customer loop are either inconvenient, capable of handling only a single loop and do not provide overvoltage protection within the module. The instant invention provides a simple, convenient means to provide similar functions for a plurality of telephone lines, includes overvoltage protection within the module and circuitry for adding the signature thereto, is weatherproof and is readily exchangeable with other modules presently in use. The identifying signature impedance appearing across the customer line allows for interrogation by the telephone office. The module is readily replaceable with a minimum of wiring disconnects required.